Lasers have been used to provide heat energy, directly or indirectly, for the purpose of removing plaque or other obstructing materials in a corporal lumen. One such system is disclosed in Ginsburg et al. U.S. Pat. No. 4,790,310 (the '310 patent) entitled "Laser Catheter Having Wide Angle Sweep." Another such system is disclosed in Muiller et al. U.S. Pat. No. 5,066,292 (the '292 patent) entitled "Catheter System For Vessel Recanalization In The Human Body."
In the catheter device of the '310 patent, laser energy is output from a distal end via four directable optical fibers. The optical fibers are evenly spaced from one another about the lumen of the catheter. A segmented distal end portion of the catheter spreads apart to enlarge the optical fiber spacing. The expanded spacing of optical fibers redirects the path of the emitted laser energy.
In the catheter device of the '292 patent, laser energy is also output from a distal end via directable optical fibers. The optical fibers are arranged in jointed groups. Upon expansion of the catheter a distal end portion of the ring of optical fibers is expanded only in selected regions between jointed groups.
Although the devices disclosed in the above patents provide directable laser energy, several disadvantages exist. As the distal end portion of each device expands, the laser energy per area (power density) necessarily decreases since each optical fiber or optical fiber group moves apart from adjacent optical fibers. This causes the power density to decrease at a rate inversely proportional to the expansion of the distal end portion. Decreased power density will increase the time and possibly reduce the effectiveness of the procedure to remove the corporal lumen obstruction.
There continues to be a need to provide a cost effective catheter for efficient delivery of directable radiant energy, such as laser, for ablation of obstructions in a corporal lumen.